Polycyclic aromatic hydrocarbons (PAHs) are abundant in space, as
their vibrational features are consistent with Aromatic Infrared Bands
(AIBs) at 3.3, 6.7, 7.7, 8.6, 11.3 \(\mu \) m which are among the
strongest emission features observed in the interstellar medium (ISM)
[1]}. In the ISM, especially in the photodissociation
regions where high ultraviolet (UV) fields exist, PAHs may get
electronically excited by absorbing ultraviolet and visible photons.
The excited PAHs subsequently dissipate their excess energy via
several competing channels: ionization, infrared emission,
isomerization, and fragmentation [2]}.
PAH fragmentation is believed to play an important role in the
catalytic formation of H\(_2\)  [3]}, [4]}, as a source
of small hydrocarbons [5]}, and as a part of more complex
top-down interstellar chemistry [6]}. It is also an
indicator of whether or not PAHs can survive in harsh interstellar
environments [7]}, [8]}. Experimental techniques,
such as imaging photoelectron photo-ion
coincidence (iPEPICO) [9]}, [10]}, infrared multiple-photon
dissociation (IRMPD) [11]}, [12]}, and temperature
programmed desorption (TPD) [4]} have been used to
investigate the fragmentation of PAHs in neutral [4]},
cationic [15]}, and hydrogenated
form [16]}, providing mass-to-charge ratios of fragments.
The resulting mass spectra are usually dominated by H, 2H/H\(_2\)  and
C\(_{2n}\) H\(_x\)  loss [17]}, [18]}, [19]}, [15]}, [21]}, [22]}. The lack of structural
information in mass spectra of intermediate and product fragments,
however, strongly limits the understanding of the detailed processes
and pathways in PAH fragmentation.
